液氮溶浸对不同煤阶含水煤样渗流特性的影响  

Effect of liquid nitrogen immersion on seepage characteristics of water-bearing coal samples of different coal ranks

作　　者：张磊[1] 田苗苗 曾世攀 郭鲁成 卢硕 唐俊[2] ZHANG Lei;TIAN Miao-miao;ZENG Shi-pan;GUO Lu-cheng;LU Shuo;TANG Jun(School of Mines,State Key Laboratory of Coal Resources and Safe Mining,China University of Mining&Technology,Xuzhou,Jiangsu 221116,China;School of Safety Engineering,China University of Mining and Technology,Xuzhou,Jiangsu 221116,China)

机构地区：[1]中国矿业大学矿业工程学院煤炭资源与安全开采国家重点实验室,江苏徐州221116 [2]中国矿业大学安全工程学院,江苏徐州221116

出　　处：《岩土力学》2022年第11期3015-3026,共12页Rock and Soil Mechanics

基　　金：国家自然科学基金项目(No.52174129);中国科协“青年人才托举工程”项目(No.2017QNRC001)。

摘　　要：中国包含多种煤阶煤层,由于煤质、地质条件等差异,不同煤层中的水分赋存情况也具有较大差异性。煤阶、饱水度作为影响液氮低温致裂效果的两个重要因素,有必要对其进行深入研究。为此,分别选择褐煤、烟煤与无烟煤3种煤阶煤样,并制备得出饱水度分别为0%、33%与99%的煤样进行液氮溶浸处理,使用摄像机定点拍摄、观察煤样表面宏观裂隙处理前后的演化规律,并对煤样进行氮气渗流试验。试验结果表明:液氮溶浸后褐煤因产生的一条与多条贯穿裂隙发生整体结构上的断裂,烟煤表面有新裂隙产生,原生宏观裂隙有一定的扩展与延伸,无烟煤表面宏观裂隙无明显发育;煤样饱水度越高,液氮的致裂增透效果越显著;液氮溶浸对3种煤阶煤样的致裂增透效果关系为:褐煤>烟煤>无烟煤,在完全干燥状态下,由于热应力不足以破坏颗粒间链接,烟煤与无烟煤的增透效果近似相等;对于褐煤,液氮溶浸处理对完全干燥状态下的煤体即产生有效致裂,渗透率平均增幅高达559.35%,对于烟煤,在饱水度为33%和99%的状态下,液氮溶浸对煤体具有明显致裂效果,渗透率平均增幅分别为330.60%和448.77%,对于无烟煤,在饱水度为99%的状态下液氮溶浸处理才能对煤体产生有效致裂,渗透率平均增幅为185.53%。There exist coal seams of various ranks in China. Due to differences in coal quality and geological conditions, the occurrence of water in different coal seams is different. Coal rank and water saturation are two important factors affecting the cracking effect of liquid nitrogen at low temperature, which are worthy of further study. Therefore, three ranks of coals, including lignite, bituminous and anthracite coal samples, were chose to be treated as coal samples with 0%, 33% and 99% water saturation respectively for liquid nitrogen immersion. The camera was used to shoot and observe the variation of macroscopic cracks on the surface of coal samples before and after treatment. The coal sample was tested with nitrogen seepage. The experimental results were as follows. 1) The lignite after liquid nitrogen immersion was destroyed as a whole due to one and several penetrating cracks. New cracks were created on the surface of bituminous coal, and the original macroscopic cracks were expanded and extended compared with those before treatment. Macroscopic cracks on the surface of anthracite have no visible changes. 2) The higher the saturation of coal sample was, the better the fracturing and enhancing permeability effect of liquid nitrogen was. 3) The ranking of fracturing and enhancing permeability effect of liquid nitrogen immersion on three coal rank coal samples is as follows: lignite> bituminous coal>anthracite coal, but in the completely dry state, enhancing permeability effects of the bituminous coal and anthracite coal were approximately the same because the thermal stress was not enough to destroy the inter particle linkage. 4) Liquid nitrogen immersion could effectively crack the completely dry lignite, and the permeability of treated lignite increased by 559.35% on average. Liquid nitrogen immersion could significantly crack the bituminous coal with 33% and 99% water saturation, and the average increase of permeability of treated bituminous coal was 330.60% and 448.77%, respectively. For the anthracite with

关 键 词：煤阶 饱水度 液氮溶浸 无因次渗透率 渗透率增幅 

分 类 号：TD712[矿业工程—矿井通风与安全]